multiple choice) Muscles of the human body must pull several hundred Newtons of force to effect rotations of the arms and body trunk around the elbow joints and pelvis. Why? A) These muscles have very large cross-section areas B) These muscles have very small cross-section areas C) These muscle attach to bones with the smallest of lever arm distances D) These muscle attach to bones with the largest of lever arm distances

multiple choice) Muscles of the human body must pull several hundred Newtons of force to effect rotations of the arms and body trunk around the elbow joints and pelvis. Why? A) These muscles have very large cross-section areas B) These muscles have very small cross-section areas C) These muscle attach to bones with the smallest of lever arm distances D) These muscle attach to bones with the largest of lever arm distances

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter9: Statics And Torque

Section: Chapter Questions

Problem 35PE: Unlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in...

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Unlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in Figure 9.44, is attached relatively far from the joint, enabling large forces to be exerted by the back teeth. (a) Using the information in the figure, calculate the force exerted by the lower teeth on the bullet. (b) Calculate the force on the joint.
The forearm shown below is positioned at an angle with respect to the upper arm , and a 5.0- kg mass is held in the hand. The total mass of the forearm and hand is 3.0 kg, and their center of mass is 15.0 cm from the elbow. (a) What is the magnitude of the force that the biceps muscle exerts on the forearm for =60 ? (b) What is the magnitude of the force on the elbow joint for the same angle? (c) How do these forces depend on the angle ?
We analyzed the biceps muscle example with the angle between forearm and upper arm set at 90°. Using the same numbers as in Example 9.4, find the force exerted by the biceps muscle when the angle is 120° and the forearm is in a downward position.
Two children push on opposite of a door during ply. Both push horizontally and perpendicular to the door one child pushes with a force of 17.5 N at a distance of 0.600 m from the hinges, and the second child pushes at a distance of 0.450 m. What force must the second child exert to keep the door from moving? Assume friction is negligible.
A device for exercising the upper leg muscle is shown in Figure 9.39, together with a schematic representation of an equivalent lever system. Calculate the force exerted by the upper leg muscle to lift the mass at a constant speed. Explicitly show how you follow the steps in the Problem-Solving Strategy for static equilibrium in Applications of Statistics, Including Problem-Solving Strategies
Explain the reason for holding the shopping bags towards the elbow leads to less muscle effort.
Triceps muscle Biceps m-40 kg m- 25 kg Calculate the force the biceps muscle must exert to hold the forearm and its load as shown in the Figure? * O 480 N.m O None of the answers O 400 N.m O 0.480 kN O 48 N
Unlike most of the other muscles in our bodies, the masseter muscle in the jaw, as illustrated in the figure, is attached relatively far from the joint, enabling very large forces to be exerted by the back teeth. This is shown in the figure below, where a person is biting down on a bullet placed between the back teeth. (FM = 200 N and r. = 3.7 cm.) M= 2.9 cm Masseter muscle гeaction (a) Using the information in the figure, calculate the magnitude of the force exerted by the teeth on the bullet. (b) Calculate magnitude of the force on the joint.
In the figure below, the biceps muscle exerts force supporting a perpendicular forearm and a book, Suppose we replace the book with an elastic exercise rope that obeys Hooke's Law. Assume its force constantk = 433 N/m. Triceps muscle Biceps V muscle PHYSICS m, = 4.3 kg CG m, = 2.2 kg CG Wa 38 cm (a) How much is the rope stretched (past equilibrium) to provide the same force w as before the book was replaced? Assume the rope is held in the hand at the same location as the book. (Enter your answer in cm.) cm (b) What force (in N) is on the biceps muscle If the exercise rope is pulled straight up so that the forearm makes an angle of 24° with the horizontal? Assume the biceps muscle is still perpendicular to the forearm. (Assume the same stretch in the rope as part (a). Enter the magnitude.)
We analyzed the biceps muscle example with the angle between forearm and upper arm set at 90° (see figure below). Triceps muscle Biceps V muscle PHYSICS CG FET ma Wh CG Wa Find the force exerted by the biceps muscle when the angle is 135° and the forearm is in a downward position. (Assume that r, = 6.0 cm, r = 14 cm, r, = 40 cm, m, = 2.0 kg, and m, = 3.4 kg. Enter the magnitude.)
In the figure below, the biceps muscle exerts a force supporting a perpendicular forearm and a book. Suppose we replace the book with an elastic exercise rope that obeys Hooke's Law. Assume its force constant k = 453 N/m. Triceps muscle Biceps U muscle PHYSICS m, = 4.3 kg CG FE m, = 3.7 kg Wo CG 4.0 cml Wa 16 cm 38 cm (a) How much is the rope stretched (past equilibrium) to provide the same force w, as before the book was replaced? Assume the rope is held in the hand at the same location as the book. (Enter your answer in cm.) |cm (b) What force (in N) is on the biceps muscle if the exercise rope is pulled straight up so that the forearm makes an angle of 18° with the horizontal? Assume the biceps muscle is still perpendicular to the forearm. (Assume the same stretch in the rope as part (a). Enter the magnitude.)
Hold your upper arm vertical and your lower arm horizontal with your hand palm-down on a table, as shown below. If you now push down on the table, you'll feel that your triceps muscle has contracted and is trying to pivot your lower arm about the elbow joint. If a person with the arm dimensions shown pushes down hard with a 12-lbs force, what force must the triceps muscle provide, in Ibs? Ignore the mass of the arm and hand in your calculation. (Hint: Where should you choose as the pivot point?) Your answer needs to have 3 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement. Triceps 30 cm 2.4 cm